A plurality of domestic appliances or kitchen appliances, like for example hand blenders, having a power source being electrically connectable to an electrical motor for driving a processing tool is already known from the state of the art. The known domestic appliances usually comprise a safety system in order to avoid an unintended start of the processing tool, which may lead to injuries, especially if the processing tool comprises movable blades or knifes.
DE 10 2005 038 919 A1 discloses a hand mixer with a battery serving as a power source, said power source being electrically connectable to an electrical motor for driving a processing tool. The known hand mixer comprises a manually switchable first mechanical switch, a so-called safety switch, and a manually switchable second mechanical switch, a so-called on/off-switch. The first mechanical switch and the second mechanical switch, respectively, may be independently switched from a first position into a second position by a finger of the user's hand grasping the hand mixer. There is further provided an electronic safety system, said electronic safety system comprising first means for detecting the position of the first mechanical switch and second means for detecting the position of the second mechanical switch. The electronic safety system is constructed such that the motor will only be connected to one or both poles of the power source if both mechanical switches are switched into their second position and if the first mechanical switch is switched into its second position before the second mechanical switch is switched into its second position. If the user does not switch the first mechanical into its second position, the second mechanical switch nevertheless may be switched into its second position, however, the second mechanical switch is electronically locked by the electronic safety system, so that the motor will not be connected to the power source even if the second mechanical switch is actuated. Thus, the opportunity of unintentionally operating the motor and the processing tool, respectively, is reduced and the safety of the hand mixer is increased.
The known hand mixer has proved himself insofar as the safety could be increased by using a safety switch and a separate on/off-switch in combination with an electronic safety system for electronically locking the on/off-switch if the safety switch is not actuated. However, high demands are made for such an electronic safety system, in order to avoid any malfunctions which may lead to an unintended start of the motor and the processing tool, respectively. These demands are for example described in IEC Standard 60335 of the International Electrotechnical Commission. Thus, extensive and time-consuming tests have to be carried out in order to comply with said standard and demands, respectively, so that the production of the known hand mixer with its electronic safety system is complicated and time-consuming. Further, if it is intended to change the software of the electronic safety system, said tests have to be carried out again, which leads to the aforementioned disadvantages. Above this, even if the safety of the known hand mixer is increased by using an electronic safety system, the safety of said hand mixer should further be increased in order to avoid malfunctions and thus injuries caused by an unintended start of the processing tool.
It is therefore an object of the present invention to provide a domestic appliance with two mechanical switches in combination with an electronic safety system, said domestic appliance on the one hand ensuring a further increased human safety and on the other hand reducing the efforts of testing the electronic safety system, so that the production of the domestic appliance is simplified. It is a further object of the present invention to provide a method for operating a domestic appliance increasing the safety of the domestic appliance and reducing the expenditure in manufacturing and testing.